Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does reveal the mutation (create) and the return value (new template id), which is useful, but it does not mention any side effects (e.g., whether the placeholder substitution is validated, whether the template can be used immediately, or if there are any restrictions on body length). For a mutation tool without annotations, this is a notable gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loads the core action (create a new SMS template), and immediately provides the most critical usage detail (placeholder syntax). It is efficient and every sentence adds value, with no fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the low complexity (2 parameters, no output schema, no nested objects) and 100% schema coverage, the description is largely complete. It covers the creation purpose, placeholder usage, and return value. The only minor gap is the lack of explicit guidance on when to use this vs. update or list, but that is secondary given the clear verb.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, with each parameter having a description (body: 'Template body with {{variable}} placeholders.', name: 'Short label so users can pick it from a list.'). The description adds the specific placeholder names ({{first_name}}, etc.) and confirms that the body parameter accepts these placeholders, which is helpful beyond the schema. However, it does not explain the required status or any constraints, but the schema already covers those.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb ('Create'), the resource ('a new SMS template'), and the key behavior (placeholder substitution). It distinguishes from siblings like sms_templates_list and sms_templates_update because it explicitly says 'create' and mentions the returned template id, which is unique to creation. The sibling list contains many similar create tools, but the description is specific enough to disambiguate from them.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explains what to do (create a new template) and mentions placeholder substitution, but does not explicitly state when to use this tool vs alternatives (e.g., sms_templates_update for editing, or sms_templates_list for browsing). No exclusions or alternative references are given, leaving some inference to the agent based on the verb 'create'.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.